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SubjectRe: [PATCH linux v2 1/3] drivers: w1: add hwmon support structures
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On 07/12/2017 02:41 PM, Jaghathiswari Rankappagounder Natarajan wrote:
> This patch has changes to w1.h/w1.c/w1_family.h generic files to
> add (optional) hwmon support structures.
>
> Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>
> Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
> ---
> v2
> - made changes to support hwmon_device_register_with_info mentioned by Guenter.
>
> drivers/w1/w1.c | 21 ++++++++++++++++++++-
> drivers/w1/w1.h | 2 ++
> drivers/w1/w1_family.h | 2 ++
> 3 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
> index e213c678bbfe..c37e21597c5c 100644
> --- a/drivers/w1/w1.c
> +++ b/drivers/w1/w1.c
> @@ -32,6 +32,7 @@
> #include <linux/sched.h>
> #include <linux/kthread.h>
> #include <linux/freezer.h>
> +#include <linux/hwmon.h>
>
> #include <linux/atomic.h>
>
> @@ -659,13 +660,31 @@ static int w1_family_notify(unsigned long action, struct w1_slave *sl)
> return err;
> }
> }
> -
> +#ifdef CONFIG_HWMON

HWMON can be built as module. If so, this won't be enabled, even if W1 is also built as module.
Better would be

#if IS_REACHABLE(CONFIG_HWMON)

I personally would probably use

if (IS_REACHABLE(CONFIG_HWMON) && fops->chip_info) {

to avoid the ifdef and to ensure that the code always compiles. But that is a personal preference.

> + if (fops->chip_info) {
> + struct device *hwmon
> + = hwmon_device_register_with_info(&sl->dev,
> + "w1_slave_temp", sl,
> + fops->chip_info,
> + NULL);
> + if (IS_ERR(hwmon)) {
> + dev_warn(&sl->dev,
> + "could not create hwmon device\n");
> + } else {
> + sl->hwmon = hwmon;
> + }
> + }
> +#endif
> break;
> case BUS_NOTIFY_DEL_DEVICE:
> if (fops->remove_slave)
> sl->family->fops->remove_slave(sl);
> if (fops->groups)
> sysfs_remove_groups(&sl->dev.kobj, fops->groups);
> +#ifdef CONFIG_HWMON
> + if (fops->chip_info && sl->hwmon)
> + hwmon_device_unregister(sl->hwmon);
> +#endif

Not completely understanding the code, I may be wrong, but wouldn't it be
better to remove the sysfs group and the hwmon device before calling
remove_slave() ?

> break;
> }
> return 0;
> diff --git a/drivers/w1/w1.h b/drivers/w1/w1.h
> index 129895f562b0..74ef1a543856 100644
> --- a/drivers/w1/w1.h
> +++ b/drivers/w1/w1.h
> @@ -83,6 +83,7 @@ struct w1_reg_num
> * @family: module for device family type
> * @family_data: pointer for use by the family module
> * @dev: kernel device identifier
> + * @hwmon: pointer to hwmon device
> *
> */
> struct w1_slave
> @@ -99,6 +100,7 @@ struct w1_slave
> struct w1_family *family;
> void *family_data;
> struct device dev;
> + struct device *hwmon;
> };
>
> typedef void (*w1_slave_found_callback)(struct w1_master *, u64);
> diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
> index 10a7a0767187..9001851e1316 100644
> --- a/drivers/w1/w1_family.h
> +++ b/drivers/w1/w1_family.h
> @@ -55,12 +55,14 @@ struct w1_slave;
> * @add_slave: add_slave
> * @remove_slave: remove_slave
> * @groups: sysfs group
> + * @chip_info: pointer to struct hwmon_chip_info
> */
> struct w1_family_ops
> {
> int (* add_slave)(struct w1_slave *);
> void (* remove_slave)(struct w1_slave *);
> const struct attribute_group **groups;
> + const struct hwmon_chip_info *chip_info;
> };
>
> /**
> --
> 2.13.2.932.g7449e964c-goog
>
> --
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